US3824342A - Omnidirectional sound field reproducing system - Google Patents

Omnidirectional sound field reproducing system Download PDF

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Publication number
US3824342A
US3824342A US00251742A US25174272A US3824342A US 3824342 A US3824342 A US 3824342A US 00251742 A US00251742 A US 00251742A US 25174272 A US25174272 A US 25174272A US 3824342 A US3824342 A US 3824342A
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United States
Prior art keywords
signals
sound
microphones
sound field
theta
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Expired - Lifetime
Application number
US00251742A
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English (en)
Inventor
R Christensen
J Gibson
Roy A Le
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RCA Licensing Corp
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RCA Corp
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Priority to US00251742A priority Critical patent/US3824342A/en
Priority to DE2317124A priority patent/DE2317124A1/de
Priority to CA169,399A priority patent/CA976090A/en
Priority to IT23574/73A priority patent/IT984179B/it
Priority to AU55116/73A priority patent/AU481910B2/en
Priority to CH646473A priority patent/CH565494A5/xx
Priority to DD170651A priority patent/DD104673A5/xx
Priority to JP48051041A priority patent/JPS5215201B2/ja
Priority to BR3322/73A priority patent/BR7303322D0/pt
Priority to NL7306404A priority patent/NL7306404A/xx
Priority to GB2174673A priority patent/GB1432153A/en
Priority to DK253273AA priority patent/DK137110B/da
Priority to SE7306449A priority patent/SE378969B/xx
Priority to FR7316629A priority patent/FR2183974B1/fr
Priority to AT410273A priority patent/AT350294B/de
Priority to ES414567A priority patent/ES414567A1/es
Application granted granted Critical
Publication of US3824342A publication Critical patent/US3824342A/en
Assigned to RCA LICENSING CORPORATION, TWO INDEPENDENCE WAY, PRINCETON, NJ 08540, A CORP. OF DE reassignment RCA LICENSING CORPORATION, TWO INDEPENDENCE WAY, PRINCETON, NJ 08540, A CORP. OF DE ASSIGNMENT OF ASSIGNORS INTEREST. Assignors: RCA CORPORATION, A CORP. OF DE
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04S—STEREOPHONIC SYSTEMS 
    • H04S3/00—Systems employing more than two channels, e.g. quadraphonic
    • H04S3/02—Systems employing more than two channels, e.g. quadraphonic of the matrix type, i.e. in which input signals are combined algebraically, e.g. after having been phase shifted with respect to each other

Definitions

  • the present invention relates to systems for producing a surround stereophonic sound field which may include an arbitrary number of sound sources disposed at various azimuthal locations around a listening point in space.
  • the invention to be described contemplates describing the sound field at that point in terms of threequantities, the total sound pressure A at that point and a pair of quantities A sin and A -cos 0 indicative of the gradients (i.e., direction) of the sound pres sure at that point with respect to a reference direction.
  • the three quantities described above are produced by means of an array of, for example, four microphones located at a virtual central point in a sound field, the microphones facing outwardly from the point and being displaced from each other by equal angular increments.
  • Linear signal'combining means are coupled to the microphones for combining the outputs thereof to produce first, second and third audio frequency signals proportional to A, A cos 0 and A sin 6 representative of the total sound pressure and sound pressure gra client at the point in space.
  • Three signal transmission channels are provided for coupling the three signals to a further linear signal combining means wherein signals proportional to A, A cos 0 and A sin 0 are recombined with predetermined relative amplitudes to produce a plurality of audio frequency signals suitable for driving a like number of loudspeakers so as to recreate a surround stereophonic sound field at a listening position.
  • the three signals A, A cos 6 and A sin 6 are formed by linear, additive combinations of outputs provided by four closely spaced microphones having like cardioidal response characteristics, the microphones being directed along orthogonal axes.
  • a surroundstereophonic sound field is synthesized by linearly, additively combining a plurality of signals representative of individual sound sources to form a total sum signal A. Means are provided for multiplying the quantity A by factors proportional to cos 0 and sin 0 to form second and third directional signals A cos 0 and A sin 0.
  • FIG. 1 is a schematic, block diagram of a system constructed in accordance with the present invention which utilizes three signal transmission channels for recreating a sound field surrounding a listener;
  • FIG. 2 is a diagram of the cardioidal characteristics of two microphones shown in FIG. 1;
  • FIG. 3 is a schematic, block diagram of a portion of a system constructed in accordance with the present invention for synthesizing three signals suitable for recreating a sound field surrounding a listener.
  • each microphone 10, 12, 14 and 16 are mounted at a virtual point 18 in a sound field, the microphones 10 and 14 being disposed along a first axis and are directed towards the left front (I and right rear (R respectively.
  • the microphones l2 and 16 are disposed along a second axis orthogonal to the first and are directed towards the right front (R,) and left rear (L respectively.
  • the microphones 10, l2, 14, 16 have predetermined directional response characteristics which, in the illustrated embodiment, preferably are all equal and are of a cardioidal pattern. Two such response patterns are shown in FIG. 2 directed along the axis associated with microphones 10 and 14.
  • the patterns associated with microphones l2 and 16, as noted above, preferably are similar in shape but are directed along their associated axis.
  • Sound waves which are intercepted by the microoutputs from one or more of the microphones depending upon sound direction and amplitude.
  • the direction of a sound source with respect to the microphone array may be specified in terms of an angle 0 measured from a reference line passing through the point 18. In the discussion which follows, 0 will be specified as 0 for a frontward direction (i.e., midway between L; and R,) and increasing counterclockwise.
  • a sound source located at a point distant from the central point 18 and producing a sound pressure of amplitude A at point 18 will produce the following responses in microphones l0, l2, l4 and 16, respectively:
  • the quantity A will hereafter also be referred to as M (a main channel signal) and, as specified in equation (5) is proportional to the sum of the responses of the four microphones 10, 12, 14 and 16 asdefined by equations (1) (4) above.
  • Summing amplifier 22 arranged to provide a relative gain of 2 2, produces an output signalA cos which is defined by the expression:'
  • a sin O is thus seen to be proportional to the difference between the response of left side (L;, L,) microphones 10, 16 and the response of right side (R;, R,) microphones 12 and 14.
  • the signal A sin 9 is therefore sometimes referred to hereinafter as Y, or a left minus right signal.
  • the three signals A, A cos 9 and A sin 0 are coupled via appropriate separate transmission channels 26, 28 and '30 to reproducing means.
  • the transmission channels 26, 28 and 30 may, for example, include a storage medium such as magnetic tape on which the three signals are recorded in separate tracks for subsequent recovery in a well known manner.
  • the transmission channels may be included in an FM surround stereophonic radio system of the type described in the above-referenced Christensen patent application. 4 A
  • the outputs of transmission channels 26, 28 and 30 are coupled to linear, additive signal combining means for application to an appropriate array of loudspeakers 32, 34, 36 and 38 in a listening location 40.
  • the loudspeakers 32, 34, 36 and 38 are illustrated as arranged in a square pattern. That is, each loudspeaker is in a separate comer of a square room. Such an arrange ment is suitable for producing left front (Lf), right front (R right rear (11,) and left rear (L,') audio signals.
  • the additive signal combining means are illustrated as comprising first and second inverting amplifiers 42 and 44 supplied, respectively with A cosO and A sin 0 information, an amplifier 46 exhibiting a gain of it: and coupled to the A signal transmission channel 26 and fourlinear matrixing amplifiers 48, 50, 52 and 54 coupled, respectively, to loudspeakers 32, 34, 36 and 38.
  • the output of amplifier 46 (in the A channel) is coupled to each of matrix amplifiers 48, 50, 52 and 54 so as to provide equal signals representative of total sound pressure to allsuch amplifiers.
  • the outputs of inverters 42 and 44 and the remaining outputs of transmission channels 28 and 30 are coupled to matrix amplifiers 48, 50, 52 and 54 so as to satisfy the following relationships:
  • the illustrated arrangement for three channel transmission of surround stereophonic information also may be characterized as a uniform system. That is, regardless of the azimuthal orientation of a sound source in the original sound field, the reproduced sound source will appear to the centrally located listener in the listening room 40 asappearing from the same azimuthal orientation as the original. Furthermore, a constant amplitude sound source moving around the horizon of the original sound field will be reproduced without fluctuations in power in the listening room 40 where four like loudspeakers 48, 50, 52 and 54 are employed.
  • the sound field components produced by each of the speakers 32, 34, 36 and 38 for a given location (6) of a sound source in the original sound field may be calculated by means of the equations set forth above.
  • the loudspeakers 32, 34, 36 and 38 will provide relative outputs of 0.85A, 0.15A, 0.15A and 0.85A, respectively.
  • the equal outputs of loudspeakers 32 and 38 will produce a virtual sound source midway between such loudspeakers.
  • a standing wave (non-directional) sound component of 0.15A radiated by all four loudspeakers may be considered to be superimposed upon the traveling wave component (e.g., 0.7A) appearing to come from a phantom source midway between loudspeakers 32 and 38. It should be noted that standing wave information is carried by the M signal channel.
  • a sound source along one of the axes (e.g., Ly) associated with microphones 10, 12, 14 and 16 produces response in the principal speaker (e. g., I equal to that of the original sound source and one-half that response in the flanking speakers (e.g., L,- and R;).
  • I the principal speaker
  • flanking speakers e.g., L,- and R;
  • M, X and Y signals representative of a desired sound field may be formulated utilizing a different microphone technique than that shown in FlG. 1.
  • a series of separate magnetic recording tracks 100, 102, 104, etc., each representing the sound contribution of a single musical instrument are shown.
  • Such multi-track recordings are conventionally used in commercial sound recording studios.
  • the information on each track 100, 102, 104 of the tape is converted by means of a conventional magnetic pickup head 106, 108, 110 to electrical audio frequency signals for application to an amplifier 112, 114, 116.
  • Variable attenuators (gain controls) 118, 120, 122 are provided in each signal path for control by the sound engineer.
  • each of attenuators 118, 120, 122 are coupled to a first summing amplifier 124 to produce an audio sum signal (M) as defined in connection with FIG. 1.
  • apparatus is provided in each signal path for selectively placing each sound source in a particular spatial position.
  • sine-cosine potentiometers 126, 128 and 130 of the type, for example, commonly employed as phase resolvers in the servomechanism art, are included in each signal path. Adjustment of the shaft position of the potentiometers 126, 128, 130 will determine the relative angular spatial orientations of the several sound sources in the resulting sound field.
  • third means for additively combining said plurality of electrical signals to produce a signal proportional to A sin 0.
  • said plurality of transducers comprise four like microphones disposed about a point in a sound field, said microphones being equally angularly spaced around said point and each exhibiting a cardioidal response characteristic.
  • said first additive combining means comprises a summing circuit providing a relative gain of one-half for each of signals supplied by said four microphones,
  • said second and third additive combining means providing relative gains of 2 /2 for each of said signals from. said four microphones,
  • said second combining means further providing inversion of signals fromtwo adjacent ones of said microphones and said third combining means providing inversion of signals from one of said two adjacent ones of said microphones and of signals from a third one of said microphones adjacent to said one.
  • transducers comprise a plurality of magnetic pickup devices, each associated with a corresponding magnetic sound recording track, said apparatus further comprising a like plurality of sine-cosine potentiometers coupled in circuit between each said pickup device and said second and third combining means.
  • a sound reproducing system comprising:
  • first, second, third and fourth linear additive signal combining means for coupling said transmission channels to said sound reproducing means to pro- .duce, by means of said three signals, four output signals representative of a sound field surrounding a spatial region suitable for reproduction by synthesis of said four signals from said three signals in additive and subtractive combinations.
  • L,-, Rf, R, and L correspond respectively signal A sine 6 is proportional to the difference be- Sound Sources disposed at left from, right from, tween the left side and right side sound sources deright rear and left rear locations in a sound field; fined by the expression: A Sine 6 K(Lr Rf signal A cosine 0 is porportional to the difference be tween the front and rear sound sources defined by 5 the quanmy K representing a numerical the expression: A cosine 6 V7 K(L;+ R; R, Constantr); and
  • Patent No. 3,524,342 Dated July 16 1974 en. et al.

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  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Theoretical Computer Science (AREA)
  • Acoustics & Sound (AREA)
  • Mathematical Analysis (AREA)
  • Mathematical Optimization (AREA)
  • Mathematical Physics (AREA)
  • Pure & Applied Mathematics (AREA)
  • Algebra (AREA)
  • General Physics & Mathematics (AREA)
  • Signal Processing (AREA)
  • Stereophonic System (AREA)
  • Stereo-Broadcasting Methods (AREA)
  • Stereophonic Arrangements (AREA)
  • Signal Processing Not Specific To The Method Of Recording And Reproducing (AREA)
  • Circuit For Audible Band Transducer (AREA)
US00251742A 1972-05-09 1972-05-09 Omnidirectional sound field reproducing system Expired - Lifetime US3824342A (en)

Priority Applications (16)

Application Number Priority Date Filing Date Title
US00251742A US3824342A (en) 1972-05-09 1972-05-09 Omnidirectional sound field reproducing system
DE2317124A DE2317124A1 (de) 1972-05-09 1973-04-05 Vorrichtung zur erzeugung von ein raeumliches schallfeld darstellenden signalen
CA169,399A CA976090A (en) 1972-05-09 1973-04-24 Sound reproducing system
IT23574/73A IT984179B (it) 1972-05-09 1973-04-30 Sistema per la riproduzione dei suoni
AU55116/73A AU481910B2 (en) 1972-05-09 1973-05-02 Sound reproducing system
DD170651A DD104673A5 (it) 1972-05-09 1973-05-07
CH646473A CH565494A5 (it) 1972-05-09 1973-05-07
NL7306404A NL7306404A (it) 1972-05-09 1973-05-08
JP48051041A JPS5215201B2 (it) 1972-05-09 1973-05-08
GB2174673A GB1432153A (en) 1972-05-09 1973-05-08 Sound reproducing system
DK253273AA DK137110B (da) 1972-05-09 1973-05-08 Lydgengivelsesapparat.
SE7306449A SE378969B (it) 1972-05-09 1973-05-08
BR3322/73A BR7303322D0 (pt) 1972-05-09 1973-05-08 Aparelho para produzir sinais representando um campo de som
FR7316629A FR2183974B1 (it) 1972-05-09 1973-05-09
AT410273A AT350294B (de) 1972-05-09 1973-05-09 Vorrichtung zur erzeugung von der schallverteilung in einem raeumlichen bereich entsprechenden signalen
ES414567A ES414567A1 (es) 1972-05-09 1973-05-09 Perfeccionamientos en sistemas de reproduccion sonora.

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US00251742A US3824342A (en) 1972-05-09 1972-05-09 Omnidirectional sound field reproducing system

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US (1) US3824342A (it)
JP (1) JPS5215201B2 (it)
AT (1) AT350294B (it)
BR (1) BR7303322D0 (it)
CA (1) CA976090A (it)
CH (1) CH565494A5 (it)
DD (1) DD104673A5 (it)
DE (1) DE2317124A1 (it)
DK (1) DK137110B (it)
ES (1) ES414567A1 (it)
FR (1) FR2183974B1 (it)
GB (1) GB1432153A (it)
IT (1) IT984179B (it)
NL (1) NL7306404A (it)
SE (1) SE378969B (it)

Cited By (14)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3940559A (en) * 1974-04-18 1976-02-24 Cbs Inc. Compatible four channel recording and reproducing system
US3970788A (en) * 1971-10-06 1976-07-20 Cooper Duane H Monaural and stereo compatible multidirectional sound matrixing
US4042779A (en) * 1974-07-12 1977-08-16 National Research Development Corporation Coincident microphone simulation covering three dimensional space and yielding various directional outputs
DE2711299A1 (de) * 1976-03-15 1977-09-22 Nat Res Dev Tonwiedergabesystem
DE2728325A1 (de) * 1976-07-01 1978-01-05 Nat Res Dev Mehrkanal-schallwiedergabesysteme
US4074084A (en) * 1975-11-05 1978-02-14 Berg Johannes C M Van Den Method and apparatus for receiving sound intended for stereophonic reproduction
US4119798A (en) * 1975-09-04 1978-10-10 Victor Company Of Japan, Limited Binaural multi-channel stereophony
US4236039A (en) * 1976-07-19 1980-11-25 National Research Development Corporation Signal matrixing for directional reproduction of sound
US4392019A (en) * 1980-12-19 1983-07-05 Independent Broadcasting Authority Surround sound system
US6041127A (en) * 1997-04-03 2000-03-21 Lucent Technologies Inc. Steerable and variable first-order differential microphone array
US20050270906A1 (en) * 2002-03-18 2005-12-08 Daniele Ramenzoni Resonator device and circuits for 3-d detection/receiving sonic waves, even of a very low amplitude/frequency, suitable for use in cybernetics
US20070147634A1 (en) * 2005-12-27 2007-06-28 Polycom, Inc. Cluster of first-order microphones and method of operation for stereo input of videoconferencing system
US20140016801A1 (en) * 2012-07-11 2014-01-16 National Cheng Kung University Method for producing optimum sound field of loudspeaker
US10631085B2 (en) 2018-05-07 2020-04-21 Crestron Electronics, Inc. Microphone array system with Ethernet connection

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1494751A (en) * 1974-03-26 1977-12-14 Nat Res Dev Sound reproduction systems
JPS5187002A (en) * 1975-01-29 1976-07-30 Nippon Telegraph & Telephone 4 chanerusutereohoshiki
HU190912B (en) * 1983-09-07 1986-12-28 Polyak,Gabor,Hu Method and apparatus for making stereoscopic sound effects

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3746792A (en) * 1968-01-11 1973-07-17 P Scheiber Multidirectional sound system

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1359509A (en) * 1970-06-15 1974-07-10 Scheiber P Decoder apparatus for use in a multidirectional sound system

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3746792A (en) * 1968-01-11 1973-07-17 P Scheiber Multidirectional sound system

Non-Patent Citations (5)

* Cited by examiner, † Cited by third party
Title
Analysing Phase Amplitude Matrices, Scheiber, AES Preprint, 10/71. *
Discrete Matrix Multichannel Stereo, Cooper & Shiga, Journal of Audio Engr. Society, Presented 10/7/71. *
Four Channels and Compatibility, 10/70, Scheiber, AES Preprint. *
Multi Channel Matrix Encoding by Cooper, Presented 10/7/71, AES Convention. *
Multichannel Stereo Matrix Systems: An Overview by Eargle, Journal AES, July/August 1971. *

Cited By (19)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3970788A (en) * 1971-10-06 1976-07-20 Cooper Duane H Monaural and stereo compatible multidirectional sound matrixing
US3940559A (en) * 1974-04-18 1976-02-24 Cbs Inc. Compatible four channel recording and reproducing system
US4042779A (en) * 1974-07-12 1977-08-16 National Research Development Corporation Coincident microphone simulation covering three dimensional space and yielding various directional outputs
US4119798A (en) * 1975-09-04 1978-10-10 Victor Company Of Japan, Limited Binaural multi-channel stereophony
US4074084A (en) * 1975-11-05 1978-02-14 Berg Johannes C M Van Den Method and apparatus for receiving sound intended for stereophonic reproduction
DE2711299A1 (de) * 1976-03-15 1977-09-22 Nat Res Dev Tonwiedergabesystem
US4095049A (en) * 1976-03-15 1978-06-13 National Research Development Corporation Non-rotationally-symmetric surround-sound encoding system
US4139729A (en) * 1976-07-01 1979-02-13 National Research Development Corporation Sound reproduction system with matrixing of power amplifier outputs
DE2728325A1 (de) * 1976-07-01 1978-01-05 Nat Res Dev Mehrkanal-schallwiedergabesysteme
US4236039A (en) * 1976-07-19 1980-11-25 National Research Development Corporation Signal matrixing for directional reproduction of sound
US4392019A (en) * 1980-12-19 1983-07-05 Independent Broadcasting Authority Surround sound system
US6041127A (en) * 1997-04-03 2000-03-21 Lucent Technologies Inc. Steerable and variable first-order differential microphone array
US20050270906A1 (en) * 2002-03-18 2005-12-08 Daniele Ramenzoni Resonator device and circuits for 3-d detection/receiving sonic waves, even of a very low amplitude/frequency, suitable for use in cybernetics
US7263034B2 (en) 2002-03-18 2007-08-28 Andrea Chiesi Resonator device and circuits for 3-D detection/receiving sonic waves, even of a very low amplitude/frequency, suitable for use in cybernetics
US20070147634A1 (en) * 2005-12-27 2007-06-28 Polycom, Inc. Cluster of first-order microphones and method of operation for stereo input of videoconferencing system
US8130977B2 (en) 2005-12-27 2012-03-06 Polycom, Inc. Cluster of first-order microphones and method of operation for stereo input of videoconferencing system
US20140016801A1 (en) * 2012-07-11 2014-01-16 National Cheng Kung University Method for producing optimum sound field of loudspeaker
US9066173B2 (en) * 2012-07-11 2015-06-23 National Cheng Kung University Method for producing optimum sound field of loudspeaker
US10631085B2 (en) 2018-05-07 2020-04-21 Crestron Electronics, Inc. Microphone array system with Ethernet connection

Also Published As

Publication number Publication date
FR2183974A1 (it) 1973-12-21
DK137110B (da) 1978-01-16
JPS5215201B2 (it) 1977-04-27
AU5511673A (en) 1974-11-07
BR7303322D0 (pt) 1974-07-11
DK137110C (it) 1978-06-19
GB1432153A (en) 1976-04-14
NL7306404A (it) 1973-11-13
JPS4955301A (it) 1974-05-29
AT350294B (de) 1979-05-25
DE2317124A1 (de) 1973-11-22
CH565494A5 (it) 1975-08-15
FR2183974B1 (it) 1978-02-10
DD104673A5 (it) 1974-03-12
IT984179B (it) 1974-11-20
ATA410273A (de) 1978-10-15
CA976090A (en) 1975-10-14
ES414567A1 (es) 1976-02-01
SE378969B (it) 1975-09-15

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